United States Patent [191

[111

4,030,955

Antonio et al.

[45]

June 21, 1977

[54]

METHOD OF MANUFACTURE

3,770,536 11/1973

DECORATIVE LAMINATE TO PROVIDE GLUE ADHERABLE BACK SURFACE [75]

Inventors: Christ‘) Antonio, Princeton; wyman F. Uhl, Sterlin , both of Mass. .

_

.

.

g

[73] Asslgnee' gilttggl?gsl?zzssystems’ Inc" [22] Filed:

Nov. 5, 1974

[51] [58]

[56]

FOREIGN PATENTS OR APPLICATIONS 1,221,477 6/1960 France ............................. .. 156/230 Primary Examiner—William A. Powell A ttorney, A gent,

or

Fzrm' A rth ur T . G roemnger; '

Norman Friedman; Morris 1. Pollack [57]

ABSTRACT

A heat and pressure consolidated laminate in which the

[21] Appl. No.: 521,054 [52]

Haigh ................................ .. 156/71

back most sheet has fused thereto a surface ?lm com

US. Cl. ............................. .. 156/235; 156/288; 156/289; 428/152; 428/914 Int. Cl.2 ....................................... .. B32B 31/00 Field of Search ......................... .. 156/230-241, 156/288, 289, 323; 428/ 152, 914 References Cit d ~ e UNITED STATES PATENTS

2,680,700

6/1954

Meyers .... .., ................. .. 156/289 X

3,511,731

5/1970

Raynal ......................... .. 428/530 x

position of polyvinyl alcohol, animal glue or starch which serves a glue line to which conventional glues adhere, the ?lm being adhered to the back most sheet during heat pressure consolidation of the laminate by transferring the same from a release layer to the back most surface of the laminate and fusing the transferred ?lm to the thermosetting resin impregnated in the back Sheet 2 Claims, 1 Drawing Figure

_/-\/

OVERLAY- SHEET9\_5 L PRINT SHEET llc/b

CORE STOCK

13

L

1 >5

E

i

GLUE LINE /9 RELEASE FILM 17 GLUE LINE /9 CORE STOCK

/3

.0 a

/5

L

PRINT SHEET [Iv-b OVERLAY SHEET9 L

US. Patent

June 21, 1977

4,030,955

OVERLAY SHEET9\J§ PRINT SHEET l/V'F CORE STOCK

I3

I [

GLUE LINE /.9 RELEASE FILM l7 GLUE LINE /9 I

CORE STOCK

/3

l I

PRINT SHEET "wk OVERLAYS H EET 9 E

13/5

I

4,030,955

1

2

compositions readily adhere to all conventionally used glues, for adhering a laminate to a supporting substrate. The glue line is adhered to the back surface inciden tal to conventional laminate manufacture by transfer ring the same from a release medium used to separate

METHOD OF MANUFACTURE DECORATIVE LAMINATE TO PROVIDE GLUE ADHERABLE BACK SURFACE BACKGROUND OF THE INVENTION 1. Field of the Invention

laminate assemblies during manufacture.

In making decorative laminates, a plurality of sheets are impregnated with a thermosetting resin and stacked in superimposed relation with a decorative sheet placed

DRAWING FIG. 1 is an exploded view of two sheet assemblies about to be formed into decorative laminates in a lami

on top.

nating press.

.

The assembly is then heat and pressure consolidated.

DETAILED DESCRIPTION

Generally, more than one laminate is formed at one

Referring to FIG. 1, a conventional laminating press

time by inserting a plurality of assembled sheets in a

stack with each assembly being separated by a release

is schematically illustrated comprising heated platens l

sheet which allows the individual laminates to be sepa rated after heat and pressure consolidation.

and 3 which are adapted to apply heat and pressure to superimposed sheet assemblies 5 and 7. Assemblies 5 and 7 are placed back to back and each of these assem

The laminates so formed are than bonded to a sub

strate such as plywood, hardboard, asbestos board, particle board, and the like by the use of adhesives such as contact adhesives, urea-formaldehyde, white glues (polyvinyl acetate emulsions), hot melts, phenolic or resorcinol-formaldehyde epoxy, coal tar, animal glues

20

blies 5 and 7 comprise a top layer 9 which comprises an overlay sheet adapted to provide wear and abrasion resistance to the underlying print sheet 11. Beneath the

print sheet 11 are several layers of core stock 13 which impart rigidity to the laminate. Each of the sheets are impregnated with a thermosetting resin with generally a and the like. Before the laminate can be applied to its supporting 25 phenolic being used in the core stock 13 and a clear

melamine formaldehyde beingiused in the print and

substrate, it must be ?rst sanded on its back most sur

overlay sheets 9 and 11. It is to be understood that other thermosetting resins could be used. A release medium 15, constructed in accordance the laminates, has some of the release material on its 30 with the present invention, comprising a release film 17, separates the assemblies 5 and 7 so that after heat surface transfer to the back surface of the laminate. By and pressure consolidation of the assemblies into ?n back most surface, it is meant to refer to the exposed ished decorative laminates the same may be readily ?at surface of the laminate which is furthest away from

face. This is because conventionally used adhesives will not directly adhere to the phenolic impregnated in the back sheet. In addition, the release medium separating

the decorative sheet.

separated. In addition, opposite surfaces of release ?lm

'

The sanding operation is an expensive step in the process and adds to the cost of the product. While the use of contact adhesives avoids this problem to a cer

35

17 have glue lines 19 adhered thereto which, simulta neously with heat and pressure consolidation of the assemblies 5 and 7, release from ?lm 17 to the back

. most core sheets 13' of each of the assemblies 5 and 7. tain extent, the expense involved in using such adhe Glue line 19 permits the laminate to be adhered by use sives together with the fact that the laminate manufac turer can not predict what type of adhesive will be 40 of conventional adhesives to a supporting substrate. While not essential, the back most sheets 13’ can be used, makes sanding a standard step in laminate manu creped to further enhance adherability of the surface to facture. The sanding operation has an additional short conventionally used glues. coming where exceedingly thin laminates are made as A feature of the present invention is that release the laminates frequently become damaged during the medium 15 is merely substituted for release sheets sanding operation because of their extreme thinness. currently being employed in the laminating industry This results in rejects. and therefore, at minimal increase in manufacturing For a considerable period of time, the laminating cost, the subsequent sanding step is eliminated. industry has been seeking some method of perfecting a Glue line 19 may be formed by coating the back technique that would allow the manufacture of a deco rative laminate capable of directly adhering, without a 50 sheet 13' with the ?lm forming glue line material prior to lamination. The ?lm then fuses to the phenolic or sanding operation, to a supporting substrate by use of other thermosetting resin in the back sheet 13' during conventional low priced adhesives.

2. Prior Art

The only known pertinent prior art in US. Pat. Re

lamination. The release ?lm 17 may be selected from any ?lm

No. 27644 which issued to Peter Barnard Kelley et al 55 material which does not soften and/or become tacky during heat and pressure consolidation. For this pur wherein the back surface of a decorative laminate is pose, polypropylene, polybutylene, polyethylene tere coated with a polyvinyl acetate composition. This coat phthalate and the like may be used. The thickness of ing delaminates with moderate temperature ?uctuation ?lm 17 is not critical and it is limited only by the ease and does not in practice serve as a glue line for urea formaldehyde and phenol resorcinol which are two of 60 of handling which generally requires a ?lm of % mil or more in thickness. the most commonly used adhesives for securing a lami The material forming the glue line 19 is a critical nate to a supporting substrate. feature of the present invention. For reasons not clearly BRIEF DESCRIPTION OF THE INVENTION understood, only three materials have been found satis

The present invention provides the back most sheet 65 factory. These are polyvinyl alcohol, animal glue and of a decorative laminate with a glue line comprising a

starch. Animal gelatin, which is a more re?ned type of

?lm composition selected from polyvinyl alcohol, ani

animal glue, also functions satisfactorily and as used herein, is included in the de?nition of animal glue. Of

mal glue or starch. The glue lines formed from these

4,030,955

3

these, polyvinyl alcohol is preferred. The thickness of

4

Filler, cross linking agents and wetting agents may be added to the glue line 19. The amounts of polyvinyl

pressure was applied as is conventionalin decorative laminating at 350° F for 12 minutes. The assemblies were then removed and reaily’sepa rated from the release medium. The coating on the release medium was completely transferred to the lami~

alcohol or animal glue used should be suf?cient to form

nates.

the glue line 19 is not critical but generally it should be over l/lO ofa mil.

a substantially continuous ?lm capable of integral transfer during heat and pressure consolidation. Gener ally, this requires at least 10% of the glue to be polyvi nyl alcohol or animal glue of a dry solid basis and pref

The laminates so formed were then adhered to a

supporting substrate of particle board using urea-for maldehyde and phenol resorcinol. '

The laminates together with the adhered substrates of particle board were tested by ?rst heating and then cooling the laminates over wide temperature ranges. The supporting particle board was then pulled away

erably the glue line 19 is at least 49% by weight polyvi nyl alcohol. While not necessary, a ?ller such as talc may be

added to improve glue bond especially when adhesives

. and -a break occured internally of the particle board

such as urea-formaldehyde is used to adhere the lami nate to its supporting substrate.

rather than along the glue line as would otherwise occur with a non-sanded back sheet.

Cross linking agents such as formaldehyde and/or glyoxal may also be used to assure that polyvinyl alco

hol is water insolubilized assuring the prevention of moisture swell in the ?nished laminate. A wetting agent such as that marketed under the

EXAMPLE II The same coating material prepared in Example I was 20 prepared except that animal glue was substituted for

polyvinyl alcohol. The results were substantially identi cal to those found in Example I.

trademark Calgon (sodium hexamethaphosphate) may be added to enhance the wettability of the surface. The following is an Example of the present invention.

The following coating composition was prepared

EXAMPLE Ill 25

comprising on a dry solid basis: ,Polyvinyl Talc

Calgon (sodium hexamethaphosphate Formaldehyde Glycerol

l00 parts 43 parts

10 parts 1.33 parts L33 parts

30

The same coating material prepared in Example I was prepared except that starch was substituted for polyvi nyl alcohol. The results were substantially identical to those found in Example I. We claim:

-

1. A process for forming a laminate comprising the

steps of assembling a plurality of superimposed plies of thermosetting resin impregnated sheets between heated platens, placing a release medium between the

A coating batch was prepared by mixing a 20 percent aqueous solution of polyvinyl alcohol with a 50 percent 35 heated platens and adjacent the back surface of the bottom most ply of said sheets, transferring a glueable slurry of talc and Calgon with the proportions being as coating from said release medium to said back surface above set forth. A 37 percent aqueous solution of for while consolidating said assembly by applying heat and maldehyde and a 40 percent solution of glycerol was pressure through said heated platens and applying su?i then added to the batch in proportional amounts as 40 cient heat to cure said resin thereby ?rmly anchoring above set forth. said glueable coating to said bottom-most ply, said ' This batch was then diluted with water so as to pro vide a viscosity of 800 centipoises so as to make the

glueable coating being formed of a substance including

same suitable for coating. The coating batch was then coated on a polypropyl

nyl alcohol, animal glue and starch.

a material selected from the group consisting a polyvi 2. A process as de?ned by claim 1 comprising a sec

ene ?lm, which was about one mil thick, by use of a

ond assembly of a plurality of superimposed plies of

wire rod to provide a coating thickness of one mil. This was dried to 200° F for 2 minutes and the polypropyl

thermosetting resin impregnated sheets, placing said

second assembly back to back with said ?rst mentioned assembly with said release medium therebetween and the same thickness with the coating material so as to provide identical coatings on both surfaces of the ?lm. 50 transferring a second glueable coating to the back sur face of said second assembly during heat and pressure The release medium so formed was then placed be ‘consolidation. tween two assemblies of sheets as in FIG. 1 that were to SI * * it * be formed into decorative laminates. The heat and

' ene coating was then coated on its opposite surface to

55

65

UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRECTION PATENTNQ:

4,030,955

DATED

June 21,

:

lNVENTOR(S) 1

1977

Christo Antonio et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, Line 43 "a", second occurrence, should be

-—

of

--

.

Signed and Scaled this Sixteenth Day 0'. May I978 |SF.~\I.| .4 mm:

RU'I'II ('. MASON

A trusting Officer

LU'I‘RELLI'I F. PARKER

Acting Commissioner of Parents and Trademarks